package study.datastructure.doublep.leetcode;/**
 * @program: datastructure
 * @author: lcy
 * @create: 2025-02-13 11:46
 */

/**
 2025/2/13,
 */

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * 双指正
 */
public class s1 {

    /**
     * 三数之和
     * @param nums
     * @return
     */
    public List<List<Integer>> threeSum(int[] nums) {

        List<List<Integer>> result = new ArrayList<>();
        if (nums == null || nums .length < 3)
            return result;
        Arrays.sort(nums);
        int len = nums. length;
        for (int i = 0; i < len - 2; i++) {
            if(nums[i]>0) break; // 后序数更大 无法和为零
            if (i >0 && nums[i] == nums[i-1]) continue; // 去重

            int left = i +1;
            int right = len -1;
            while (left < right) {
                int sum = nums[i] + nums[left] + nums[right];

                if (sum < 0) {
                    left++;
                } else if (sum > 0) {
                    right--;
                }else {
                    result.add(Arrays.asList(nums[i],nums[left],nums[right]));
                    while (left <right && nums [left] == nums [left + 1]) left++;
                    while (left <right && nums [right] == nums [right - 1]) right--;

                    left++;
                    right--;
                }

            }


        }
        return result;
    }


}
